Temporary shelters have gained increasing popularity in recent times, and the number of situational applications for these shelters continue to grow. Typically, these temporary shelters are those which include an assembled framework structures that collapse into a stored state that is relatively compact yet which expands into an erected state over a much larger surface are. A rood covering is provided for shade, for protection against the rain or other natural elements, or for other shelter purposes. Side panels may be used either to provide a display background or in the form of protective netting against insects, and other complementary structures may be employed with the basic framework to increase the application for these shelters. Shelters, such as those described with respect to the present invention, are often employed for purposes of recreation, fairs, bazaars, outdoor exhibitions, and food and beverage vending, to name a few.
One such example of an expandable, portable canopy shelter is shown in my U.S. Pat. No. 4,779,635, issued Oct. 25, 1988. The canopy structure shown in the preferred embodiment of that Patent shows a framework unit formed by a plurality of upright corner members that are expandably connected to one another by side-scissor assemblies, and, in an erected state, roof support members extend upwardly and radially inwardly, to a central apex. The roof support members are pivotally connected at one end to the apex and at the other end to a top of a respective upright corner member. The roof support members are expandable, preferably by telescoping with one another, and may be latched into an extended position when the canopy framework is erected. The canopy framework may be collapsed by moving the corner supports together. This is permitted since the scissor assemblies interconnecting the corner supports are on slide brackets. As the framework is collapsed, each roof support member is telescoped together and the apex portion is dropped from a peak position down through the horizontal plane defined by the upper ends of the corner supports. The apex continues to drop through center until it reaches a stored position wherein it is adjacent to the corner support members, which are in turn, adjacent to one another. In the erect state, a flexible covering extends over the roof support members and is supported by the framework.
Another example of an expandable/collapsible shelter is shown in my earlier U.S. Pat. No. 4,641,676. This Patent shows a portable canopy structure again having a framework that maybe collapsed into a stored state yet may be expanded and erected for use. The framework includes a plurality of upright support members which are interconnected by a plurality of edge scissor assemblies. An internal scissor assembly is provided to support a central post, and a flexible covering extends across the top of the supports and is supported at a center by the central post. The structure is also similar to that described in U.S. Pat. No. 4,607,656, issued Aug. 26, 1986 to Carter.
Although the structures shown in the above-referenced patents provide significant advantages over earlier prior art structures, especially in the relative ease of both expansion and collapse, these two types of structures nonetheless have some drawbacks. For example, with respect to the first described structure, Lynch #'635, the need to move the apex portion through the plane defined by the tops of the corner support members (i.e. "through center"), causes some inconvenience both during the erection of the structure and during its collapse. This procedure requires some manipulation of the roof support structure directly during the assembly and take-down of the device. On the other hand, the structure shown in Lynch #'676 patent and in the Carter patent has the disadvantage of including an internal scissoring structure which eliminates some of the headroom provided for persons sheltered by the canopy structure. Furthermore, both Lynch #'767 and Carter show structures that are under compressive forces so that, when the scissor assemblies are subjected to forces transversely of the scissor assembly plane, the combination of the two forces can result in substantial bowing of the scissor assemblies and distortion of the canopy framework.
Therefore, despite the advantages provided by the above-referenced structures and other shelter devices, there remains a need for a portable shelter, especially having a relatively small dimension, which can be quickly and easily erected and taken down. There is a further need for such a shelter framework wherein roof supports are erected automatically as the framework is expanded. There is a further need for an extremely light-weight structure which can be used as a cabana for such applications as a portable dressing room, manhole cover, latrine shelter, or shower enclosure.